The most frequent methods used are batch, fed-batch, repeated batch, and
continuous for lactic acid production. Fed-batch cultures produce higher
quantity of lactic acid than in continuous cultures. Continuous cultures
on the other hand produce higher productivity of lactic acid as well as
the possibility to continue the process for a longer period of time. The
different approaches in producing lactic acid can be found in the table
below.

Organism

Fermentation mode

γ (lactic acid)
g/L

Productivity
g/(L.h)

Lactobacillus casei SU No 22+

fed-batch, coimmobilization

47.0

2.0

Lactobacillus lactis WS 1042

Enterococcus faecalis RKY1

batch,

95.7

4.0

repeated batch, cell-recycle via membrane

93.2

6.4

Lactobacillus rhamnosus ATCC 10863

batch,

~ 120.0

2.1

continuous, cell-recycle via membrane

92.0

57.0

Lactobacillus casei ssp. Rhamnosus ATCC
11443

continuous, cell-recycle via immobilization

22.4

9.0

Lactobacillus delbrueckii NRRL B445

fed-batch, in situ removal via solvent extraction

~ 23.1

0.2

Lactococcus lactis IO-1 JCM 7638

batch, in situ removal via electrodialysis

~ 39.0

0.9

Lactobacillus rhamnosus IFO 3863

batch,

98.0

1.9

continuous, in situ removal via electrodialysis

~ 20.0

8.2

Lactobacillus helveticus CNRZ 303

continuous, cell-recycle via membrane

55.0

7.1

Lactobacillus delbrueckii CECT 286

continuous, in situ removal via ion-exchange resin

26.1

10.4

General Process of
Lactic Acid Production Using Whey as Raw Material

Type of ReactorContinuous Stirred Tank Reactor

Raw Material
Whey

Steps

Whey
proteins are separated from the acid whey.

The lactose in the whey permeate is converted to lactic acid in an
un-aerated bioreactor by a strain of lactic acid bacteria which does
not require any further supplements, to lactate.
This method produces high concentrations of biomass. High and
economic lactic acid productivities are also achieved by cell
recycling using an integrated cross-flow-filtration unit.

The product recovery is carried out by
bipolar electrodialysis,
converting lactate directly into the free acid
Diagram illustrating bipolar electrodialysis